Related Party Transactions and Major Customers (Tables)

9 Months Ended

Sep. 30, 2015

Related Party Transactions [Abstract]

Schedule of Related Party Transactions [Table Text Block]

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
	(in millions)
Corporate service charges	$	40	$	41	$	126	$	117

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

CenterPoint Houston’s transmission and distribution revenues from major customers are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
	(in millions)
Affiliates of NRG	$	222	$	222	$	578	$	552
Affiliates of Energy Future Holdings Corp.	$	67	$	59	$	170	$	140